现有书目表 book,包含字段:价格 price (float) ,类别 type(char); 现在查询各个
A.
的平均价格、类别名称,以下语句正确的是( )。
B.
select avg(price),type from book group by type
C.
select count(price),type from book group by price
D.
select avg(price),type from book group by price
E.
select count (price),type from book group by type